Three-dimensional viewing systems are rapidly developing, due to the vast areas in which such technology is useful. The duplication of normal visual perception has applications in the areas of: undersea (submersible) maintenance and search equipment; robotics; high-security surveillance; hazardous materials handling; entertainment; training simulator technologies; and education, to name a few. The goal of such systems is to substitute a computer-generated, recorded, or real-time remote reality for the user's current reality. Such systems may include audio, visual, and motion inputs to the user in order to create a total experience. The video aspect of such systems is known as stereoscopic viewing. Stereoscopy provides two views, i.e., a left and a right view, that are integrated by the viewer to give the impression of viewing three-dimensional objects.
The quality of stereoscopic systems depends largely on the field of vision presented to the viewer, clarity of the images, correctness of the colors and intensity of the images. A normal full field of vision for an adult can be defined by the area of visual attention coupled with the area of peripheral vision. The area of visual attention is that field in which the eye can maintain attention and sharp focus. For a single average eye this area spans about 120.degree. vertically and horizontally in front of the eye. The area of peripheral vision extends from the area of attention along the temporal periphery and enhances the perception of the area of attention. For a single average eye, peripheral vision allows an additional 60.degree. of vision along the horizontal plane. For purposes of this application, it will be assumed that an area spanning 120.degree. vertically and 180.degree. horizontally defines a full field of vision for an average adult. The clarity, color, and intensity of the images displayed for viewing should be nearly equal to those of the real images that are being depicted.
Stereoscopic systems include three major components: image-gathering; image-processing; and presentation. For example, a conventional movie camera often serves as the image-gathering component. The image-processing component would then be the equipment and methods for retaining the images on film, i.e., film development. The presentation component could then be a movie screen and any viewer optical systems necessary for creating proper viewer perception. The present invention is related to a presentation component useful in a stereoscopic viewing system.
An example of a stereoscopic system is anaglyphic 3-D. The presentation component of an anaglyphic 3-D system consists of a screen and colored lenses worn by the viewer. The images displayed on the screen are left and right images that are projected through colored filters, i.e., a red and a blue filter, and superimposed on the screen. Conventionally, the colored lenses worn by the viewer coincide with the colored filters and thus separate the left and right views. The color-filtering lenses are mounted in eyeglass-type frames. In this manner, the left images are filtered into the left eye and the right images are filtered into the right eye, with all other images being blocked from view. Such a system suffers from the inability to achieve full and true image color, the reduction of image brightness, and the need for a true display system, i.e., clear screen display, to alleviate "ghosts" created by transient color surrounding the displayed images. Additionally, the field of vision in the described system is limited by the dimensions of the viewing glasses and the dimensions of the screen display.
A similar two-display system is the field sequential system. In such a system, the display, i.e., screen image, alternates between left and right images rather than superimposing them upon one another. The presentation component includes polarized, color-filtering, or piezoelectric glasses. The lenses are synchronized with the screen display. The synchronization causes the glasses to allow only left eye vision when the left image is displayed, and only right eye vision when the right image is displayed. Drawbacks in such a system include flickering of the images if a high number of frames per second is not achieved, loss of image intensity, and possible limited field of vision as a result of the use of eyeglass-type lenses and limited screen dimensions.
Certain stereoscopic viewing systems have replaced viewing glasses with special optics. One such system utilizes separate left and right LCD television screens mounted in a helmet in front of each eye. Wide-angle binocular optics are situated between the viewer and the screens. The optics are required to ensure that the left and right images properly overlap and are brought into focus. Image intensity is reduced in the optical system due to diffraction. Additionally, orientation of the viewer's eyes with the optics must be correct to avoid losing the images at the exit pupils and to avoid obstruction of the images by the lens frame.
Certain of the above-noted problems have been addressed in the area of recorded imaging. For example, the video industry has extended the display field of vision using multiple video screen displays, thereby increasing the illusion of reality by providing a wider field of vision. However, this particular solution may be inapplicable to real-time viewing because the uses for the stereoscopic technologies differ so widely. For example, a very small stereoscopic system is desirable for flight technology, i.e., an astronaut should be equipped with a helmet-mounted display rather than a large standard projection screen for viewing activities outside a space capsule.
As noted, in present stereoscopic viewing systems, images are generally dim because of the reduction in light intensity due to color and optical filtering; true color is difficult to achieve; full field of vision is not provided; and viewer orientation requirements are often restrictive. One result of these drawbacks is that an altered total visual reality is not achieved. Such a total visual reality would present images to a viewer, causing the viewer to accept those images as "real" and thus completely replacing the viewer's actual reality. An example of total versus a partial alteration in reality can be illustrated using holographic 3-D. If a holographic image of a glass is projected on a table, then the viewer's actual reality is only partially altered, since the surrounding environment remains the same. However, if it were possible to holographically project new furniture and walls along with the glass, and all existing furniture and walls were masked, then the viewer's actual reality would be altered. Clues such as screen edges, dimness, color alterations, eyepiece edges, and orientation requirements all have a negative effect on a stereoscopic system's ability to create a total visual reality completely distinguishable from the viewer's actual reality. The present invention provides the means for creating total visual reality, while it overcomes the abovenoted problems and others in the prior art.